1. Field of the Invention
The invention relates to a sealing arrangement for sealing between a flow regulator and an oxygen cylinder.
2. Description of the Related Art
In treatments for respiratory system diseases such as pulmonary emphysema or chronic bronchitis, oxygen inhalation is known as one of the most effective treatments. A small capacity portable oxygen cylinder is generally used when a patient is out of a hospital or his or her house. The oxygen cylinder contains high pressure oxygen gas and is provided with a shut-off valve. A flow regulator, for controlling the oxygen flow to the patient, is connected to the shut-off valve with an o-ring or a sealing member clamped therebetween. A metallic protection ring is provided around the o-ring. When the oxygen gas contained in an oxygen cylinder is exhausted or almost exhausted, the oxygen cylinder is replaced with a new one. The shut-off valve is closed and the flow regulator is detached from the shut-off valve. At that time, if the on-off valve is closed, a substantial volume of oxygen gas, which is filled within the flow regulator, blows out of it when the flow regulator is detached from the shut-off valve of the oxygen cylinder. Detachment of the flow regulator deforms the o-ring clamped between the flow regulator and the shut-off valve which results in electrostatic charge in the o-ring. The static electricity charged in the o-ring induces electric potential in the metallic protection ring relative to the shut-off valve and the flow regulator. A spark may be generated between the metallic protection ring and the shut-off valve and/or the flow regulator when the o-ring is apart from the shut-off valve, which may result in an accidental fire if there is combustible material near the oxygen cylinder.
The invention is directed to solve the prior art problems, and to provide an arrangement for sealing the connection between a shut-off valve attached to an oxygen cylinder and a flow regulator, which arrangement is prevented from an accidental fire due to the discharge of the oxygen gas or oxygen enhanced gas which has been filled in the flow regulator.
According to one feature of the present invention, there is provided an arrangement for sealing between a flow regulator and a shut-off valve attached to an oxygen cylinder. The shut-off valve includes a casing which is adapted to be mounted to an oxygen cylinder containing oxygen gas or an oxygen enhanced gas, a side wall defining a part of the casing. A female outlet port is defined in the side wall of the casing. The flow regulator includes a metallic cylindrical body which has first and second end faces. A yoke extends from the first end face of the cylindrical body. A screw bolt, which has an end facing the first end face of the cylindrical body, operates with the yoke to clamp the casing of the shut-off valve between the first end face of the cylindrical body and the end of the screw bolt. A male inlet port extends from the first end face of the cylindrical body into the female outlet port of the shut-off valve to receive the oxygen gas or the oxygen enhanced gas. A sealing member is provided around the inlet port of the flow regulator so that the o-ring is clamped between the first end face of the cylindrical body of the flow regulator and the casing of the shut-off valve when the flow regulator is secured to the shut-off valve. The sealing member is made of an electrically conductive rubber material.
The sealing member may be an o-ring provided around the inlet port, and a metallic protection member is provided around the o-ring for protecting the o-ring from wear and tear. According to one embodiment, the rubber material preferably has a volumetric resistivity of not more than 1.0xc3x971010 xcexa9cm.
According to another feature of the invention, an arrangement for sealing between a flow regulator and a shut-off valve attached to an oxygen cylinder is provided. The shut-off valve includes a casing which is adapted to be mounted to an oxygen cylinder containing oxygen gas or an oxygen enhanced gas. A female outlet and a positioning recess port are defined in the side wall of the casing. The flow regulator includes a metallic cylindrical body which has first and second end faces. A metallic positioning pin extends from the first end of the cylindrical body to engage the positioning recess of the shut-off valve. A yoke extends from the first end of the cylindrical body. A screw bolt, which has an end facing the first end of the cylindrical body, operates with the yoke to clamp the casing of the shut-off valve between the first end face of the cylindrical body and the end of the screw bolt. A male inlet port extends from the first end face of the cylindrical body into the outlet port of the shut-off valve when the flow regulator is attached to the shut-off valve. A sealing member is provided around the inlet port of the flow regulator so that the sealing member is clamped between the first end face of the cylindrical body of the flow regulator and the casing of the shut-off valve when the flow regulator is secured to the shut-off valve. A metallic protection member for protecting the sealing member from wear and tear is provided around the sealing member. The metallic protection member has a thickness which allows the metallic protection member to contact the first end of the cylindrical body of the flow regulator and/or the side wall of the shut-off valve.
The thickness of the metallic protection member is preferably smaller than that of the sealing member and larger than 80% of that of the sealing member. According to an embodiment of the invention, the sealing member may comprise an o-ring provided around the inlet port of the flow regulator, and the metallic protection member comprises a protection ring provided around the o-ring. In this case, the thickness of the sealing member is defined by the diameter of the o-ring. The protection ring may include an inner peripheral groove for snugly holding the o-ring. The inner peripheral groove of the protection ring may have a rounded sectional shape having a radius of curvature larger than that of the section of the o-ring or a polygonal sectional shape.
According to another embodiment of the invention, the metallic protection member comprises a protection plate provided around the o-ring. The protection plate includes a positioning hole engaging the metallic positioning pin of the flow regulator to provide an electric circuit for discharging the static electricity charged in the o-ring.
According to another embodiment of the invention, the metallic protection member comprises a protection ring provided around the o-ring. A metallic clip is provided around the protection ring. The metallic clip includes an arm portion engaging the metallic positioning pin of the flow regulator to provide an electric circuit for discharging the static electricity charged in the o-ring.